Some engines include a fixed group of cylinders that may be selectively activated and deactivated in response to vehicle conditions. For example, during light vehicle driver demand conditions, a fixed group of engine cylinders may be deactivated to conserve fuel. If vehicle driver demand increases, the same group of cylinders may be reactivated to meet the vehicle driver demand. Such engines may improve fuel efficiency over similar engines that operate with all cylinders active all of the time; however, cylinder reactivation delays may reduce engine responsiveness and deactivating the same cylinder all of the time may cause uneven degradation between engine cylinders.
Other engines have been developed that may deactivate or activate any engine cylinder at virtually any time depending on select vehicle operating conditions. Further, these engines may vary which cylinders are activated and deactivated so that wear between cylinders may be more even. Nevertheless, these engines may transmit vibrations related to the activation and deactivation of cylinders to the vehicle and its occupants. The engine vibrations may be mitigated so as to not disturb vehicle occupants by not allowing selected cylinder firing fractions and/or cylinder deactivation patterns during predetermined conditions. However, some vibrations may be still be noticeable to vehicle occupants during some engine operating conditions. Therefore, it may be desirable to seek to reduce the possibility of transmitting engine vibration to vehicle occupants during a broader range of engine operating conditions.
The inventors herein have recognized the above-mentioned issues and have developed an engine method, comprising: increasing an actual total number of engine cylinder modes that include active cylinders according to an engine cylinder mode region of an engine cylinder activation map via a controller in response to a change of engine speed or engine load, the cylinder mode region adjusted in response to a change in vehicle mass; and activating and deactivating engine cylinders in response to the change of engine speed or engine load.
By adjusting a range of an engine cylinder mode region of an engine cylinder activation map, it may be possible to provide the technical result of reducing the possibility of disturbing vehicle occupants when cylinder mode changes are made. In particular, an engine speed and load range where additional active engine cylinder modes and additional deactivated engine cylinder modes are provided may be increased or decreased in size so that cylinder modes that may influence vibrations felt by vehicle occupants may be avoided in response to changes in vehicle mass. The vehicle's mass and location of mass of the vehicle may affect transmission of vibrations related to modes where one or more engine cylinders are deactivated. As such, adjusting size of one or more engine cylinder mode regions may help avoid the possibility of disturbing vehicle occupants due to vibrations that may be related to cylinder modes where one or more engine cylinders may be deactivated.
The present description may provide several advantages. For example, the approach may improve vehicle drivability. Further, the approach provides adjustments to which cylinder modes are allowable responsive to location of vehicle mass. In addition, the approach may also compensate for vibrations when a trailer is towed by the vehicle.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.